Sun outage

This topic contains 53 replies, has 12 voices, and was last updated by  jimimaseye 10 months, 3 weeks ago.

Viewing 25 posts - 1 through 25 (of 54 total)
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  • #5745

    Ben
    Member

    In a few days time it’s that time of year again. During 10 or 15 minutes or so, around noon time, your TV signal will be much reduced, possibly losing the ability to lock. It’s not SES playing tricks but sun outage – the sun will pass (nearly) directly behind the Astra satellites and blind your dish, so to speak.
    Inconvenient for most, but it offers a nice opportunity to calibrate your quality readings.
    Attached is a plot of some measurements I took last year on my Linux boxes.
    The yellow line indicate not-correctable errors resulting in more or less blocking, and the picture disappears at just above 6 dB. The total drop is another indicator. It can be computed using your geographical location and size of the dish. For details see here.

    #5791

    Derek
    Member

    Thanks Ben, learning something every day. I’ve computed date and time of expected drop but now have to measure it. Guess the easiest way for me with only CrazyScan is to sit in front of my PC at the expected time and just keep repeating scans and observe. Or is there a safer/easier way..??
    Cheers, Derek.

    #5799

    jimimaseye
    Member

    or…

    http://www.satellite-calculations.com/Satellite/suninterference.php

    and find out exact times for your location yourself.

    EDIT: didnt see the lionk in bens post. Noe you can see the full link (for those watching in black and white)

    #5829

    Derek
    Member

    Why “or” Jimi…???? That’s what I already did – Ben gave the same link in his first post..!!

    #5830

    jimimaseye
    Member

    My times:

    
    | Start ...........| End ...................| duration         
    02/28/2014 11:09:31	02/28/2014 11:12:32	03m01s
    03/01/2014 11:07:11	03/01/2014 11:14:30	07m19s
    03/02/2014 11:06:10	03/02/2014 11:15:07	08m56s
    03/03/2014 11:05:45	03/03/2014 11:15:07	09m21s
    03/04/2014 11:05:51	03/04/2014 11:14:35	08m44s
    03/05/2014 11:06:36	03/05/2014 11:13:24	06m47s
    #5869

    Ben
    Member

    Derek,
    You could, of course, manually record the CNR values. But if you want to automate things, you could use the Windows logging utility. I would change the parameters, though, and log only one transponder, but more frequently, say every 10 seconds or so. And I would choose a strong transponder from the Europa beam, so that the “normal” 2E and 2F variations are not overlain on the sun interference effects.
    It would be very interesting to see how this interference shows up in the quality readings of your Humax in comparison to the TBS2259.

    I have been tinkering with the program to support DiSEqC switches and a few more changes. Let me know, by PM or otherwise, if you want another copy.

    #5871

    Derek
    Member

    Thanks Ben. I’ll have a stab at logging one transponder as you suggest before the event. I’ll send you a PM with the outcome and can then decide if I need the updated software (at the moment I am not using a DiSEqC with the 5922).
    Cheers, Derek.

    #6080

    Derek
    Member

    Just observed my first “Sun Outage” thanks to the 5922 and Ben’s “Satellite Monitor”. Only a few dBs drop but the big one expected on 3rd March. Pity my PC aborted what was to be a 24 hour scan, so 5 hour gap till 8.30 this morning (but you can sort of guess where the plot was).

    #6215

    We are probably lucky to have the Sun Outage in these “difficult times”. ‘Tis like a beam of light from above, that directs me to that spot, where best to find that new crock of gold. In other words it’s easy to find the optimum place for me to “plant” a new dish in my small back garden, with the best line of sight!

    #6223

    jimimaseye
    Member

    My outages are happening. Thankfully the effects are starting a couple of minutes later than the prediction above, and finishing a couple of minutes earlier.

    #6258

    Derek
    Member

    Today was the “big one”…signal started to fall at about 11am, dropped to a minimum at 11.11am and fully recovered at about 11.20am. Before and after the outage, all 2E and 2F channels were showing s75-80/q100 on the Humax and about 14db CNR.
    At 11.10am and 11.12am, signal strength was unchanged at 75-80 but q was 50. At 11.11, no lock on any channel and the CNR was about 8db (confirming the outage forecast of a 6db drop). Weather fine with broken cloud cover.
    Have always read that minimum 6.5db is required for the receiver to lock – do my measurements suggest that I need 8db…??? 🙁

    #6266

    Ben
    Member

    Derek,
    That is strange, indeed. I was led to believe that the TBS5922 actually was quite accurate in it’s display of CNR, but this would suggest yours is indicating high. I also registered a drop of about 6 dB on my Famaval 100. I logged 11307V, which requires only 4.4 dB for a lock. I did not lose picture, or noticed blocking, but I did see that the Bit Error Rate started to deviate from 0 for about a 1 minute period on either side of the low. At that time the CNR indication was 5.9 dB. In addition to the minimum lock value (4.4 dB for this transponder) there is a “Quasi Error Free” rate defined, which is about 5.8 dB. (For the low frequency 2E and 2F transponders this is 7.8 dB)

    There may be another explanation, namely that your box indeed does require a better signal (for example due to tuner overload). One thing to check maybe is to look at the picture generated by your TBS5922 on your PC on tomorrow’s event. I believe there was software on the CD that came with the box.

    #6268

    Anonymous

    Hi,
    I’ve never experienced this before until a couple of days ago. I’m curious as to why the LNB working at RF can be ‘blinded’ by light in the visible spectrum. Or is there other solar radiation as well as light hitting the dish? Can someone explain this phenomenon please? The outage only lasts around ten to twelve minutes here, so not really a problem. I’m just curious.
    Cheers, Pete.

    #6273

    Derek
    Member

    Hi Ben, thanks for your observations – attached a screendump of my plot this morning (started to rain again at midday so signal already dropping). I never managed to get the “DVB Dream” software running but I can nevertheless tune into the 5922 on my PC using “Windows Media Center” (presumably I cannot do that whilst using your “Satellite Monitor” software..??).
    Cheers, Derek.

    #6284

    Nagusia
    Member

    @Derek. What do you use to make your plots? I have a windows pc with a usb satellite receiver plugged in but I have never found any signal monitoring software for windows which automatically produces a plot over time.

    #6285

    Tom
    Member

    Derek,

    You might find this works for you http://www.progdvb.com/download_progdvb.html there are other freebies on the site that work ok too, the ‘finder’ software’ is fun for dish setup.

    cheers

    Tom

    #6287

    Derek
    Member

    Ciao Nagusia, I am using a programme written by “Ben” (the one who started this topic above). I hope he doesn’t mind me saying so but if you are interested, suggest you send him a PM….

    Ciao Tom, thanks for the link, I’ll have a good look.

    Cheers, Derek

    #6288

    Derek
    Member

    Ben, sorry, just realized I didn’t follow your advice to track just one transponder (you may recall I proposed 12032 on the pan european beam being my strongest). However, I’m rather glad I didn’t as what I want to watch is the UK spot beam and today’s experience has taught me to be attentive – my setup is maybe not as robust as I thoought…!!!
    This bloody weather has convinced me that an LNB rain hood could be good also for me…

    #6289

    Steve ……
    Member

    Hi Derek…..I was just about to post….. BBC etc…still Very Very high here…8,40 Pm Still at a “Bonkers” 100% Q on the 150 Gibby…….2E still at a also “Bonkers” 70% Q on the 100cm.!…..
    Then i saw your post ..are you having probs? with 2F or 2E ?……has the beam moved a bit in Munich’s favour maybe..?…….

    #6294

    Ben
    Member

    Derek,
    Sorry for the late reply – indeed would be good to know if there is room for optimisation in your system. And, no, I don’t think you can run different programs controlling the same tuner.

    Looking at your plot, I notice that the system has a smooth curve all the way to the minimum. If it would have been indicating too high, but actually losing lock, I would have expected a flat 6 dB, or 0 values. Similar to the curve I posted on the top of this thread. (although that was done on another tuner)

    NoLock values are not displayed and to compute C/N the system needs to lock to the stream. So it would seem to me that the 5922 did not lose lock, while your Humax did. So, as you suggested above “do my measurements suggest that I need 8db…??” Perhaps it does.
    The easiest way to check this is to watch on the 5922 using your laptop and on your TV via your tuner at the same time and see if one gives up sooner than the other.

    They are on the same dish, are they not?

    #6295

    Ben
    Member

    Nagusia,
    You’re of course most welcome to use the software. Just send me a PM with your email address. Also, could you please let me know which USB tuner you use?
    Ben

    #6302

    Derek
    Member

    Ben, yes, Humax and 5922 are connected to the same dish/LNB but on different floors. Will have to perfect rapid ascents/decents or call a friend to share the task (don’t fancy moving kit, have a busy week ahead)…
    Cheers, Derek.

    #6304

    Derek
    Member

    Hi Steve, no, I’m not having problems (YET….!!!!). It’s been raining all afternoon/evening and my CNR has fallen from app. 14db at noon (dry) to app. 11db at 23.00, and is now starting to rise again after the evening low. However, the sun outage allowed me to verify that my receiver lost lock at about 8db – had always believed that this would happen at about 6.5db. Anyway, for now, I still seem to have adequate evening and rain margin so no panic…
    Cheers.

    #6307

    Steve ……
    Member

    Nice Db’s readings 🙁 …….but is it really a surprise that you lose lock first on your Humax ?…..the signal has to go through your switches and stuff….but your Gadget is connected directly ?…..Right…?……

    As a test ……why not connect the gadget thingie with switches and stuff also in the cable run..?

    For what its worth …I’m more than happy knowing ..50% signal Quallity on my Humax Freesat ..is the minimum Signal required to watch TV..!…..

    #6312

    Ben
    Member

    Pete,
    If you google on “sun outage” you get a bunch of hits. I like, for example http://www.radio-electronics.com/info/satellite/solar-effects/sun-solar-outages-basics-tutorial.php

    In essence, the sun radiates over a broad spectrum, including the frequencies the satellites are using.

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